Patents by Inventor Michael B. Shelton

Michael B. Shelton has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5540728
    Abstract: A method and apparatus of cardiac pacing, in which pacing at an increased rate is provided in response to a detected rapid drop in detected heart rate, to a stable rate below a defined threshold rate.
    Type: Grant
    Filed: September 20, 1994
    Date of Patent: July 30, 1996
    Assignee: Medtronic, Inc.
    Inventors: Michael B. Shelton, Kenneth M. Riff
  • Patent number: 5527347
    Abstract: There is provided a dual chamber pacemaker system and method for ventricular pacing to provide therapy for a patient with cardiomyopathy, this system being characterized by automatically adjusting the AV escape interval so that ventricular pace pulses are delivered at an AV delay which is optimized for HOCM and/or dialated cardiomyopathy therapy. The pacemaker system continually obtains and stores representations of a QRS wave characteristic such as duration, derived either directly from the QRS signal or from an FFRS signal, and compares duration data from one or more cycles to prior stored duration data. The system then adjusts the AV interval as a function of the duration comparison, and the direction of the last adjustment of AV escape interval. By this means, the AV escape interval is maintained at or just short of the onset of fusion, thereby automatically providing for optimally lengthened AV escape intervals consistent with full capture by the delivered ventricular pace pulse.
    Type: Grant
    Filed: February 21, 1995
    Date of Patent: June 18, 1996
    Assignee: MedTronic, Inc.
    Inventors: Michael B. Shelton, Dwight H. Warkentin
  • Patent number: 5441525
    Abstract: A rate-responsive cardiac pacemaker implements a novel scheme which detects incipient vasovagal syncope (or other episodes caused by a vasodepressive or cardioinhibitory disorder) when a) the heart rate drops below a programmable minimum size, and b) the rate after said drop is below a programmable maximum drop ending rate. The pacemaker implements a stability and intervention procedure upon the detection of an episode, in which it ignores transient drops in rate, and paces at a predetermined high rate if the drops are stable. The pacemaker then gradually reduces the pacing rate over a predetermined time to the pre-episodic level. A sleep disable feature disables the vasovagal syncope detection and therapy features during the patient's sleeping hours to reduce or eliminate false positive responses.
    Type: Grant
    Filed: May 20, 1994
    Date of Patent: August 15, 1995
    Assignee: Medtronic, Inc.
    Inventors: Michael B. Shelton, Kenneth M. Riff, Michael F. Hess
  • Patent number: 5402070
    Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.
    Type: Grant
    Filed: July 15, 1994
    Date of Patent: March 28, 1995
    Assignee: Medtronic, Inc.
    Inventors: Michael B. Shelton, Ross O. Starkson, Craig L. Schmidt, H. Toby Markowitz
  • Patent number: 5387228
    Abstract: An implantable cardiac pacemaker having programmable stimulating pulse amplitudes selectable by means of an external programming unit. The pacemaker includes charge pump circuitry for developing a stimulating pulse voltage on an output capacitor. The output capacitor is charged to a selected level identified by a multiple-bit amplitude value communicated to the implanted device from the external programmer. The pacemaker is also provided with circuitry for monitoring the depletion level of its battery and for generating an indicator signal when the battery has depleted beyond a predetermined level. Associated with the charge pump circuitry is a selectively activated comparator circuit for controlling the charging of the output capacitor. Prior to generation of the indicator signal, the charge pump circuitry remains deactivated for some programmed output amplitudes, the level of output capacitor charging being proportional to the battery voltage.
    Type: Grant
    Filed: June 22, 1993
    Date of Patent: February 7, 1995
    Assignee: Medtronic, Inc.
    Inventor: Michael B. Shelton
  • Patent number: 5370668
    Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.
    Type: Grant
    Filed: June 22, 1993
    Date of Patent: December 6, 1994
    Assignee: Medtronic, Inc.
    Inventors: Michael B. Shelton, Ross O. Starkson, Craig L. Schmidt, H. Toby Markowitz
  • Patent number: 5312453
    Abstract: A rate-responsive cardiac pacemaker in which deceleration of the pacing rate is modulated according to recent patient activity or "work". Based on signals provided from an activity sensor in the pacemaker, the pacemaker maintains and periodically recomputes a work value corresponding to the amount of patient activity detected over time. In response to a decrease in or cessation of detected patient activity, the pacemaker reduces the pacing rate, first at a more rapid deceleration rate, then at a lower deceleration rate, and then once again at a more rapid deceleration rate. The length of time during which the pacing rate is reduced at the lower deceleration rate is modulated according to the work value maintained by the pacemaker.
    Type: Grant
    Filed: May 11, 1992
    Date of Patent: May 17, 1994
    Assignee: Medtronic, Inc.
    Inventors: Michael B. Shelton, William J. Combs, Tommy D. Bennett, Michael R. Tollinger, Kenneth M. Riff